In the case of a battery for use in cold districts, such as a battery mounted on an electric vehicle, there is a risk that a battery electrolyte freezes when the battery is out of use.
A temperature fall in the battery does not lead to a fall in a battery's state of charge SOC. However, owing to the increased internal resistance, the inputable/outputable electric power tends to fall. When a battery electrolyte has frozen, the inputable/outputable electric power becomes “0” at last, and hence an electric vehicle that a battery is an energy source for vehicle running, falls into a power-running disabling state.
Therefore, it is necessary to provide a battery temperature control device configured to temperature-control by heating the battery by using a heater before a battery temperature fall develops until such time that the inputable/outputable electric power of the battery reaches the previously-discussed inconvenient state (the power-running disabling state).
One such battery temperature control device, which is configured to temperature-control by heating the battery by using a heater, has been proposed in Patent document 1.
The battery temperature control device, proposed in the Patent document 1, is configured to control or regulate a temperature of an on-vehicle battery, and also configured to heat the battery by the heater, when an outside air temperature becomes fallen to below a preset minimum temperature at a point of time when an ignition switch becomes turned OFF.